Water Distiller vs Bottled Water: The Real Cost, Worked Out

By Megahome Editorial Team· October 23, 2026 · 7 min read

TL;DR

A 580 W, 4-litre countertop distiller uses roughly 0.8–0.9 kWh per litre, so your electricity tariff sets the running cost. Here is the working, the other costs to include, and a simple formula for payback against the bottled water you buy now.

The main running cost of a home water distiller is electricity: roughly 0.8–0.9 kWh per litre for a typical 580 W, 4-litre countertop unit. Multiply that by your own tariff and compare the result with the per-litre price on your bottled-water receipts. Owners who switched from bottled water commonly estimate that their distiller paid for itself in 3 to 12 months, but your answer depends on your tariff and on what you would otherwise buy.

“A distiller pays for itself” is easy to say and hard to check. So instead of a headline number, this guide shows the working, lists the costs that are easy to forget, and gives you a formula you can fill in with your own figures. If you'd rather not do the arithmetic by hand, our cost calculator does it for you.

How much electricity does it take to make a litre of distilled water?

A distiller boils water and condenses the steam, and boiling is energy-hungry. The US CDC notes that distillation generally uses more energy and takes longer than other home water treatment methods. That is why electricity, not filters, dominates the running cost.

Here is the working for a Megahome MH-943TWS-family distiller:

Rated power: 580 W (565 W heater plus a 15 W cooling fan)
Batch: 4 litres in about 5.5–6 hours
Energy per batch: 0.58 kW × 5.5–6 h ≈ 3.2–3.5 kWh
Energy per litre: 3.2–3.5 kWh ÷ 4 L ≈ 0.8–0.9 kWh

This is an upper-end estimate, because it assumes the unit draws its full rated power for the whole batch. Treat it as a planning figure, not a laboratory measurement. A heavily scaled boiling chamber can push it higher: University of Nebraska–Lincoln Extension notes that scale reduces a distiller's efficiency and increases its electricity use.

What does that mean in money?

Multiply 0.8–0.9 kWh by the price per kWh on your electricity bill. The table uses round example tariffs in any currency and assumes a household that drinks 2 litres of distilled water a day (730 litres, or about 183 batches, a year).

Your price per kWh	Electricity per litre	Electricity per year (2 L/day)
0.10	0.08–0.09	about 58–66
0.20	0.16–0.18	about 117–131
0.30	0.24–0.27	about 175–197
0.40	0.32–0.36	about 234–263

Some real reference points from official statistics:

European Union: Eurostat puts the average household price at €0.2896 per kWh including taxes in the second half of 2025. That works out at roughly €0.23–0.26 per litre of distilled water.
Germany: one of the highest household prices in the EU in the same period, at €0.3869 per kWh, or roughly €0.31–0.35 per litre.
United States: the US Energy Information Administration reports an average residential price of 18.31 cents per kWh in July 2026, or roughly 15–17 cents per litre.

Tariffs vary by region, time of day and contract, so use the price on your own bill.

What other running costs should you include?

Activated-carbon sachets. The post-filter captures volatile compounds that can travel with the steam. Megahome's manual says to replace each sachet within 25 days, which is about 15 sachets a year in regular use, and more often if you distil water of uncertain quality.
Descaling cleaner. The manual calls for citric-acid descaling at least once a month, more often with hard water. See how to clean and descale a water distiller.
The tap water you feed in. Usually a small part of the total, but include it if you like.
Parts after the warranty. Megahome's manufacturer warranty is one year. Replacement parts exist for the faults owners report most often, such as the thermal switch, reset button, fan motor and gasket.

There is no installation or plumbing cost: a countertop distiller plugs into a normal socket.

How do you work out the payback against bottled water?

We don't quote bottled-water prices here, because they vary enormously by country, shop, brand and bottle size. Your own receipts are the best source. Then:

Find your bottled-water cost per litre: price paid ÷ litres bought.
Estimate your monthly volume. At 2 litres a day that is about 61 litres a month.
Monthly bottled cost (B) = cost per litre × litres per month.
Monthly distiller running cost (R) = litres per month × 0.8–0.9 kWh × your tariff, plus about one carbon sachet and a little descaling cleaner.
Payback in months = the distiller's purchase price ÷ (B − R).

Two things follow from that formula. The more you pay per litre today, the faster the payback. And if B and R are close, which can happen with cheap bulk water and a high electricity tariff, the distiller may never pay back on money alone. In that case the decision rests on the other factors below.

When is a distiller not the cheaper choice?

Honestly, plain tap water is cheaper than either option. Where your tap water meets your needs and you are happy to drink it, a distiller is not a money-saving device. It makes financial sense when you specifically want distilled water, whether for drinking by preference, for appliances such as steam irons and humidifiers, or for a CPAP humidifier whose manufacturer specifies it, and when you would otherwise be buying that water.

It is also less compelling if you only need a few litres a month, because the purchase price then takes many years to recover.

What about plastic, time and convenience?

Cost isn't only money. At 2 litres a day, 730 litres a year is roughly 490 bottles of 1.5 litres, or about 146 five-litre jugs, that you no longer buy, carry home or put out for recycling. The distiller fills a reusable glass or PP collection bottle instead.

Be realistic about the trade-offs, too. Owners certainly are:

Time: a 4-litre batch takes about 5.5–6 hours, so it suits households that plan ahead. At 2 litres a day you run one batch roughly every two days.
Noise: the cooling fan is the most common owner complaint. A Japanese dealer lists 56 dB at 30 cm and 52 dB at 1 m.
Heat: some owners notice the unit warms a small room while it runs.
Upkeep: rinsing after each batch and regular descaling take only minutes, but they matter.

You don't need a plug-in timer. Megahome distillers switch off by themselves when a batch is finished, and damage caused by external timers is not covered by the warranty.

How does lifespan change the maths?

The purchase price is spread over every litre the distiller ever makes, so lifespan matters as much as your tariff. University of Nebraska–Lincoln Extension says a good distiller with proper care should last 10 to 15 years. Megahome owners report 6, 8 and 9+ years of daily use, and one German owner reports about 10 years on a first unit. Durability ratings on US listings are mixed, however, and the fault named most often is the thermal reset switch, typically after one to two years and often triggered by scale baked onto the chamber floor. Regular descaling protects both your electricity bill and the hardware.

Megahome has built distillers in Tainan, Taiwan, since 1992. Its US listings have close to 5,000 Amazon ratings averaging 4.5–4.7★ as of September 2026, and value is one of the aspects owners mention most, with 77–82% of those mentions positive. For the full picture, read what nearly 5,000 owner reviews tell us. If you are still choosing between treatment methods, our comparison of distilled, reverse osmosis and spring water covers the differences beyond cost. Model details are on the MH-943TWS page, and Where to buy lists sellers in your region.

Key takeaways

A 580 W, 4-litre distiller uses roughly 0.8–0.9 kWh per litre. Electricity is the main running cost.
Cost per litre = 0.8–0.9 × your price per kWh. At the EU average for late 2025 that is about €0.23–0.26 per litre.
Add carbon sachets (each replaced within 25 days), descaling cleaner and occasional parts.
Payback = purchase price ÷ (monthly bottled spend − monthly running cost). Use your own receipts.
Tap water is cheaper than both. A distiller saves money only if you would otherwise buy bottled or distilled water.
Descaling keeps electricity use down and helps the unit last longer.

Frequently asked questions

Is a water distiller cheaper than bottled water?

Often, but not always. Compare your bottled-water price per litre with 0.8–0.9 kWh multiplied by your electricity tariff, plus a little for carbon sachets and descaling. Owners who switched commonly estimate payback within 3 to 12 months. With cheap bulk water and a high tariff, the gap can be small.

How much electricity does one batch use?

For a 580 W unit running 5.5–6 hours, at most about 3.2–3.5 kWh per 4-litre batch. Scale in the boiling chamber can increase it, so descale regularly.

Do I need to buy filters?

Only the activated-carbon post-filter sachets, which Megahome's manual says to replace within 25 days. There are no membranes or cartridges to change.

Can I lower the running cost?

Keep the chamber descaled and distil only the water you will use. If your tariff is cheaper at certain times of day, run batches then. Don't add a plug-in timer: the distiller switches itself off.

Sources

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